The present invention relates to a plug rolling mill for pipes or tubes, and more particularly to structure for manufacturing of rolls in the roll stand.
Such a plug rolling mill may include two opposing grooved rolls one of which being adjustably mounted in the roll stand in relation to the other permitting a change in the axial distance between the rolls. Particularly, the upper one of the two rolls is mounted in that fashion and here particularly on a particularly constructed carrier and support which is adjustable in up and down direction. The upper roll must be lifted after each pass for removing the very hot plug or mandrel from the rod so that a new plug can be put in place for the next pass. Plug ejection and exchange have been automated to a considerable extent. The throughput of such a mill is actually largely determined by the speed of this plug changing process. Aside from the plug exchange proper, the up and down displacement of the upper roll prior to as well as subsequent to the plug change is an added delay.